The use of scouring pads in cleaning applications is well known, and nonwoven articles have been found useful in the manufacture of such pads. Scouring articles such as hand pads and the like are available in any of a variety of shapes and sizes and can comprise a number of different materials. Known scouring articles include those made of steel wool, for example, as well as those made of one or more natural or synthetic fibers.
Conventional nonwoven articles are made by first forming a lofty web of randomly oriented discontinuous fibers which may be tensilized and crimped by prior treatment. Such webs may comprise synthetic or natural fibers as well as combinations of fibers to provide a nonwoven article useful in cleaning, scouring and other surface conditioning applications. Nonwoven webs are typically formed as air laid webs on conventional equipment and are treated with a resinous binder to bind the web fibers to one another at their contact points. Abrasive particles can be added to the binder to impart an abrasive character to the finished article for more aggressive scouring applications, for example. One successful commercial product comprising such a nonwoven web is that sold under the trade designation "Scotch-Brite" by the Minnesota Mining and Manufacturing Company of St. Paul, Minn. Low density abrasive products of this general type can be prepared by the method disclosed by Hoover et al. in U.S. Pat. No. 2,958,593.
Although nonwoven articles like those described above have enjoyed considerable success, their manufacture requires the purchase and use of expensive, complex and bulky web forming equipment. To provide a consistent and uniform appearance and structure, nonwoven webs are made using a complex multi-step layering process which orients the discontinuous fibers within each layer of the web at an angle to the web output. The layering method, however, can result in cyclic inconsistencies in the form of down line folds and web edges running at the same angle width to the web output.
Other approaches to the manufacture of scouring articles include use of continuous filaments in the manufacture of a nonwoven web. The patent literature describes the use of continuous fibers in the formation webs and mats. Exemplary scouring articles made of continuous filaments are those described in U.S. Pat. Nos. 4,991,362 and 5,025,596 to Heyer et al. These patents describe low density abrasive articles formed with continuous, unidirectional crimped filament tow with the filaments bonded together at opposing ends of the pad. Although the articles of the '362 and '596 patents have enjoyed significant commercial success as kitchen scouring pads, some shortcomings have been noted. For example, the pads of the aforementioned patents include only monodenier continuous filament, and the method for the manufacture of these pads allows for little control of the loft of the finished pad other than through the careful selection of fiber properties (e.g., crimp, feedstock grade, heat-seal character). Moreover, equipment is required for the formation of substantially identical bond areas or seals at opposite ends of the pads to thereby bind the continuous fibers of the pads and maintain the structural integrity of the pads prior to the application of a binder.
In light of the foregoing, it is desirable to provide an open, lofty nonwoven article which is easily and economically manufactured and which can be used in any of a variety of applications such as a kitchen scouring pad, for example. It is desirable to provide such an article with a consistent and uniform structure made from a nonwoven web comprising discontinuous fibers and which can easily be provided with considerable loft without requiring the aforementioned bonding or sealing equipment to bond opposing ends of the pad during the manufacturing process. It is also desirable to provide a process for the manufacture of such articles which avoids the aforementioned cyclic inconsistencies while allowing for variations in the manufacturing conditions such as the use of blends of different fiber materials as well as blends of fiber deniers. It is desirable to provide such a process for the manufacture of low density nonwoven articles having a desired loft which is not entirely dependent on the properties of the fibers used.